This paper reports on a new kind of temperature sensor operating over an extremely large temperature range at high monitoring speeds. The sensor utilizes fiber Bragg gratings inscribed into multimode single crystalline Sapphire fibers, basically providing temperature control via an optical reflection signal. The gratings operate up to 1900 °C, which is the highest temperature determined using Bragg grating so far, and allow signal processing with a temperature resolution better than ±2 K. The sensor uniquely provides fast dynamic temperature monitoring at an unprecedented rate of 20 Hz. Overall, fiber Bragg grating inside Sapphire fibers provide a new base for precise high-temperature measurement with key advantages such as signal multiplexing, large temperature bandwidth and insensitivity to electromagnetic fields.